A traditional type of internal combustion engine utilizes a cylinder and reciprocating piston arrangement. A variable-size combustion chamber is typically formed with a cylinder that is effectively closed at one end and has a moveable piston at the other end. A combustible gas, or mixture of a combustible fluid and air, is introduced into the combustion chamber and then typically compressed by the piston and ignited. The ignited gas, or mixture, exerts a force on the piston in the direction that increases the volume of the combustion chamber. The linear movement of the moving piston is then converted to rotational movement by connecting the piston on a crankshaft.
A typical reciprocating piston internal combustion engine design includes an engine block, also referred to as a cylinder block, which encases the combustion cylinders. Many engine block designs utilize material, for example aluminum, that is not well-suited for use as the internal walls of the combustion cylinders. As such, cylinder sleeves, also referred to as cylinder liners and commonly fabricated from a material more suitable to withstand the environment associated with the combustion chamber, are used to define the interior portion of the combustion cylinders and the combustion cylinder internal walls. Frequently, cylinder sleeves made of iron and are fixed in cylinder cans cast as part of the engine block and made of aluminum.
Many modern internal combustion engines include multiple cylinders, which are frequently arranged in one or more rows. Where multiple rows are used, the engine block is typically provided with two or more banks of cylinders, where each bank of cylinders includes a number of cylinders arranged in a row.
Frequently, the combustion cylinders are located in a cylinder cavity, which may be referred to as a coolant chamber when configured and adapted to circulate coolant. Engines designed to operate for extended periods, for example grater than approximately one minute, are typically manufactured with at least one coolant chamber surrounding the cylinder sleeves. The coolant chamber allows liquid coolant to circulate around and cool the cylinder sleeves.
Engines designed to operate for short periods may not include coolant chambers, thereby relying on the short period of operation to limit the total heat generated and prevent overheating and permanent deformation of the engine. Typically, engines with one or more coolant chambers are referred to as “wet block” engines, while engines without at least one coolant chamber are referred to as “solid block” engines. Most modern internal combustion engines that operate for extended periods, for example engines used in automobiles, watercraft and light civil aircraft, are wet block type engines. Engines used for high performance over a short period of time, such as those used in drag racing or tractor pulls, are frequency solid block type engines.
In a wet block type engine, a cavity for circulating coolant, also refereed to as the “water cavity,” surrounds the cylinder sleeves. Many wet block engines have the cylinders arranged in rows. While this configuration provides a number of advantages, a disadvantage with at least this arrangement is that the water cavity and the engine block are susceptible to deformation, especially when large amounts of torque or horsepower are generated. Deformation of the water cavity and the engine block can result in a host of undesirable outcomes, for example, deformation of the cylinder sleeves, fluid leakage, loss of compression, increased friction and engine seizure.
Many automobile enthusiasts are interested in increasing the torque and/or horsepower produced by commercially available stock engines. Methods by which this goal is accomplished include increasing the bore and/or stroke of the engine cylinders, adding a turbocharger, adding a supercharger, and adding a nitrous-oxide (N2O) injection system. Although changing the bore and/or stroke of the engine is frequently a very effective way to increase the engine's output, it can be relatively expensive compared to the other example methods, both in terms of time and money spent making the modification. Apparatuses useful in increasing the bore and/or stroke of an engine and method for this type of modification are disclosed in co-pending U.S. patent application No. 10/624,876, filed Jul. 22, 2003 and U.S. patent application No. 11/459,750, filed Jul. 25, 2006, and U.S. Provisional patent application No. 60/472,589, filed May 22, 2003, the entireties of which are incorporated by reference.
Due to their relative simplicity and lower cost, many automobile enthusiasts modify their stock engines to increase output using turbocharger, supercharger, or nitrous-oxide techniques. However, when the output of the stock engine is increased, the unmodified engine block is susceptible to deforming under the increased stresses that result, and problems develop. These problems include head gasket leaks, cylinder sleeve deformation, increased engine wear, loss of power and possible engine seizure. Even seemingly small leaks or slight deformation in the cylinder sleeves can have undesirable outcomes. As an example of the extent to which designers and manufactures of high performance engines will go in an attempt to minimize the adverse effect of cylinder sleeve deformation NASCAR® engineers hone their cylinders in a hot, approximately 240° F., oil bath to approximate normal operating conditions.
Difficulties with structural engine strength is not limited to performance automobiles, major automobile manufacturers have also had difficulties with the strength of their stock engine blocks. For example, Mercedes® and Honda® have used their engines as stress members in their automobiles with suspension mounts attached directly to the engine block. These attempts generally resulted in the engines failing due to their inability to carry the stress loads without deforming. One common problem included the deformation of the cylinder sleeves while the engine was running.
As such, there is a need in the industry to provide an improved internal combustion engine that resists deforming. More particularly, there is a need for an improved wet block engine with additional strength in the area surrounding the cylinder sleeves, and especially when the engine is developing high torque and/or power. There is also a need in the industry for a method to modify existing engines to increase their ability to resist deforming, especially in the area surrounding the cylinder sleeves, and especially when the engine is developing high power and/or torque.
The present invention addresses these needs and others, at least in part, by providing an internal combustion engine with an improved support structure. The present invention further provides a method for manufacturing such an engine, and a method for modifying existing engines to include additional support structure.